Mikroflora w utworach eokambru i dolnego kambru wschodniej Polski

Abstract

MICROFLORA IN THE EOCAMBRIAN AND LOWER CAMBRIAN DEPOSITS IN THE EASTERN AREA OF POLANDThe paper deals with the results of microfloristic examinations of the Eocambrian and Lower Cambrian deposits encountered in the bore hole Radzyń Podlaski (East Poland, Fig. 1).This method has for the first time been introduced to investigate the oldest sedimentary roks in the area of the Polish Lowland. Almost no trace of macrofauna have been encountered in these deposits; thus the determination of their age is very difficult.All the series distinguished by K. Lendzion (1962b) in the bore hole Radzyń Podlaski on lithological bases have been analyzed. 32 samples were examined, most of them gave positive results. The best results have been obtained from day intercalations.In general, 34 species (microflora - Tables I-Ill) of phytoplankton (Leiosphaerida and Hystrichosphaerida) and of microsopores of overground plants (Oligotriletes) have been determined the Eocambrian and Cambrian deposits found in the bore hole Radzyń Podlaski.The Cambrian deposits occurring in the area considered at a depth 943,00-1344,80 m have been referred by K. Lendzion to the Kostrzyń, Radzyń and Kaplonosy series. In the deposits of the Kostrzyń series .(943,00-1067,80 m) only single and feebly preserved forms of wide stratigraphical extent have been found. Naturally, this did not allow to determine the age of these deposits more in detail.In the deposits of the Radzyń series (1067,00-1205;00 m) and the Kaplonosy series (1206,00-1344,80 m) microflora assemblages have been established (Table 1) that point to their Lower Cambrian age. This, in particular, concerns the microflora of the Radzyń·series containing 25 species. Among them are forms typical of the Lorwer Cambrian (Archaeohystrichosphaeridium cellular Tim., Acarotnoligotriletum primigenum (Naum.) Tim.). The microflora of the Radzyń series is very similar to that determined in the deposits of the Święty Krzyż Mountains, pierced by the bore holes Kędziorka and MokradIe. The microflora of the Kaplonosy series is approximate to that determined in the bore holes situated in the vicinities of Zbrza and in the bore hole Bazów (L. Jagielska, 1965).The deposits occurring at a depth 1344,80-1669,00 m in the bore hole Radzyń Podlaski have been referred to the Eocambrian. K. Lendzion has distinguished here 3 stratigraphical members: Mazowsze, Lublin and Siemiatycze series. In these series (Table 1) the microflora is highly aboundant and points to the Eocambrian age of the deposits. As a rule the assemblages contain representatives of Leiosphaerida, among them also those of greate sizes (F. ex. Trachysphaeridium aottenuatum Tim.), a phenomenon being typical of the Eocambrian. In the Świety Krzyż Mts, similar microflora has been found in the bore hole Bazów (below a depth of 150 m)and in the bore hole Kotuszów.The microflora of the Eocambrian of Poland (particularly in the bore hole Radzyń Podlaski) shows great analogies with that newly discovered in the Pre-Cambrian deposits of Normandy (M. Roblot, 1964). This presents a possibility of biostratigraphical correlation of the oldest deposits by means of micropalaeophytologicaI methods.